Piston packing member



Sept; 14, 1937.

w. s. wA'rsoN f ISTON PACKING MEMBER Filed April 24, 1935 as a INVENTOR WILLIAM. 5. WATJOM ATTORNEYS Patented Sept. 14, 1937 UNITED STATES;

aosaoea PISTON PACKING MEMBER i William Stanley Watson.

Canada. assignor. to

Highland Park, Mioh.,

ware

wumnier. Manito i a 'Chrysler Corporation, a corporation oi Dela Application Apr-11 2's, 1935. Serial No.1'i,9il8

2 Claims. (01. some);

This invention relates to a piston packing member and is illustrated as embodied in a packing member for use with a piston in a hydraulic brake operating cylinder.

An object or the invention is to provide an expander for a yieldable packing member together with a resilient means which causes the expander to urge the packing member axially and radially into contact with the end of a piston and the inner periphery of the cylinder within which the piston reciprocates.

Another object of the invention is to provide an expander for a yleldable packing member which is positioned radially by its contact with the cylinder wall to obtain a uniform radial pressure on the packing member.

Other objects and advantages of the invention will more fully appear from the following description taken in connection with the accomgo panying drawing in which:

Fig. 1 is a sectional view oi a hydraulic brake cylinder showing a preferred form of my invention;

Fig. 2 is an end expander;

Fig. 3 is a sectional view taken on line Fig.

Fig. 4 is an end view showing in elevation the yieldable cup member; and,

Fig. 5 is a sectional view of Fig. 4. 1

Referring to the drawing, I have illustrated a hydraulic brake master cylinder housing I0 having a cylinder l2 and a reservoir I4 adapted to. contain a supply oi lubricant. Openings l6 and i8 have been provided to conduct lubricant irom the reservoir l4 to the cylinder i2. The end 20 of the cylinder is provided with an outlet fitting 22 through which lubricant from the cylinder I2 is supplied to the brakes.

A piston 24 is arranged for reciprocation in the cylinder l2 and is provided with-a rod 26 connected to an operating mechanism such as a brake pedal, not shown. The outward movement 01' the piston 24 is restricted by a wall member in the form of a washer 28 held in a counterbore by a spring ring 30. A flexible covering 32 is provided between the end of the housing ill and the rod 26 to seal the cylinder.

Heretoi'ore, packing members have been used in connection with pistons and cylinders of the type illustrated and while good results have been obtained, there are certain conditions under which they fail.

It yleldable packings such as rubber are used,

view showing in elevation the 30 taken on line 5-5 eter substantially they become hard and inelastic when. subiected to extremely cold temperatures. This causes the packings to take a permanent set and the packings do not exert a radial pressure against the cylinder wall thereby causing the lubricant to 5 leak past the packings. I

I have provided an expander for a packing member which urges the packing radially into, tight engagement with the cylinder wall although its inherent resiliency may have been destroyed by cold temperatures.

In the i'orm illustrated the packing member has a radially extending closed base portion 34 and an axially extending flange portion 36. The outer diameter of the flange 36 is substantially equal to the diameter of the cylinder l2 and the inner periphery diverges outwardly. The ex: pander is located within the flange 38 and comprises a base portion 38 and a i'rusto-conical flange portion 40. This flange 40 diverges outwardly at an angle larger than the angle of the v inner periphery of the flange 38. A radially extending flange 42 is arranged at the outer periphery oi the flange 40 and has an outer diamequal to the diameter of the cylinder l2.

The flange 42 is spaced axially from the end 01' the flange 36 and the base portions 28 and 34 are spaced axially. A coil spring 44 is arranged for compression between base portion 38; urging the expander into wedging with the flange 26, expanding the latter radially into sealing engagement with the cylinder wall I2. The spring also urges the base portion 34 into contact with the head of the piston 24.

It will be understood that while I have illustrated a preferred embodiment of my invention, various changes including the size, shape and arrangement of parts may be made without de-. parting from the spirit of my invention and it is my intention to coverby the appended such changes as may be reasonably includedwithin the scope thereof.

What I claim is:

1. In a device of the class described including 45 a cylinder and a piston having a closed head; a packing for said piston comprising a yieldable cup member having aclosed base portion and an axially extending flange portion having an outer diameter substantially equal to the outer diameter oi the piston with which it is to be used, a second cup member disposed in cooperative relationship with said yieldable cup member and having a closed base portion normally spaced from the base portion of said yieldable cupmemthe end wall 20 and the 30 her, a frusto-conicaliportion extending outwardly and axially from the outer periphery of said last named base portion and engagingthe axially extending flangeipcrtion of said"yieldable cupmember, a radially extending flange at the open end of said frusto-conical portion having an outer diameter substantially equal to the outer diameter of the flange on said yieldable cup member; and resilient means in engagement with said second cup member for urging said cup members into nested relation and for contacting the closed base portion of said yieldable packing against the closed head of the piston. v

2. In a device of the class described including wardly, a metallic cup member nested within said first named cup member having a base portion spaced from the base portion of said flrst named cup member, a frusto-conical flange at the outer periphery of said last named base portion diverging outwardly at an angle greater than the angle of the inner periphery oi" the first named flange and in engagement therewith, a radially extending flange on the outer edge portion of said frusto-conical flange having an outer diameter substantially equal to the outer diameter of said first named flange, said radial flangemaintaining said cup members,in axial alignment; and resilient means in engagement with said metallic cup member for urging said cup members into nested relation for expanding the axially extending flange oi! said rubber cup member radially.

WILLIAM STANLEY WATSON. go 

